The Custom field thing is really going great and I know with time it will be usable at all places where we fill forms like for instance payments.
I want to suggest the possibility of selecting from a list in the custom fields.

For just an example let say i create a field on the sales invoice custom field called ‘Salesperson’ and i have 3 sales people who run shift. I would like to enter their names on a list in the custom field page so that whoever makes a sale can go to the field click on the drop down and select their name.This information (Salesperson) may already be available in the server and cloud version though.

A custom field with a list you can select from can really save a lot of time spent on fields where we usually enter predefined items .